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    <title>Document</title>
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<body>
    <!-- 有且仅有h1~h6 -->
    <!-- 标题会自动加粗，且自占一行 -->
    <h1>一级标题</h1>
    <h2>二级标题</h2>
    <h3>三级标题</h3>
    <h4>四级标题</h4>
    <h5>五级标题</h5>
    <h6>六级标题</h6>

    <!-- 两个段落标签之间是有间隙的 -->
    <p>这是一个段落标签</p>
    <p>这是另外一个段落标签</p>
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